SCREW CONVEYOR FOR A SCREW SEPARATOR AND MANUFACTURING METHOD FOR A SCREW CONVEYOR

Abstract

A screw conveyor comprises a shaft, a screw flight arranged to extend helically around, and connected to the shaft at the outer circumference of the shaft, and extending in axial direction along at least a portion of the shaft, wherein the screw flight has an outer edge at the outer circumference of the screw flight, and at least one recess for receiving fibrous material is arranged in the outer edge of the screw flight. The screw flight has a cross-sectional profile with a width in the region of the outer circumference of the screw flight greater than the width in the region of the inner circumference of the screw flight. Furthermore, the invention relates to a separator device for dewatering moist masses, including liquid manure residues and/or digestates, as well as a method for additively manufacturing a screw conveyor and a use of a screw conveyor.

Claims

1-24. (canceled)

25. A screw conveyor for a separator device for dewatering moist masses, the screw conveyor comprising: a shaft extending in an axial direction along an axis of rotation; and a screw flight: arranged helically around the shaft; connected to the shaft at the outer circumference of the shaft; and extending in the axial direction along at least a portion of the shaft; wherein the screw flight is an additively manufactured metallic structure and has, on an outer circumference thereof, an outer edge in which is arranged at least one recess for receiving a fibrous material.

26. The screw conveyor according to claim 25, wherein the screw flight has a cross-sectional profile with a first width in the region of the outer circumference of the screw flight and a second width in the region of the inner circumference of the screw flight, and the first width in the region of the outer circumference of the screw flight is greater than the second width in the region of the inner circumference of the screw flight.

27. The screw conveyor according to claim 24, wherein the screw flight is produced by a wire-based additive manufacturing by means of arc welding, including gas metal arc welding (GMAW), including metal inert gas welding (MIG) and/or metal active gas welding (MAG).

28. The screw conveyor according to claim 24, wherein the screw flight is built up in layers, obtained by: applying several metallic paths by means of melting off a metal wire, wherein the paths are arranged parallel to one another and run along a thread running direction of the screw flight.

29. The screw conveyor according to claim 24, wherein the screw flight is built up in layers, obtained by: applying a first metallic path by means of melting off a metal wire, wherein the path runs along a thread running direction of the screw flight, and applying at least a second metallic path arranged parallel to the first metallic path and arranged in a first layer with the first metallic path; determining the height of the first or second metallic path in a radial direction; applying a third metallic path by means of melting off a metal wire in a second layer lying radially above the first layer, wherein the positions at which the metal wire is melted off for the application of this third metallic path is carried out in dependence of the previously determined height of the first or second metallic path; and applying several layers arranged one above the other in the radial direction, each having at least one metallic path, to form a layer stack until the layer stack reaches and/or exceeds a nominal height, wherein before the application of each new layer the height of at least one path of the previously applied layer in the radial direction is determined.

30. The screw conveyor according to claim 24, wherein the screw conveyor has at least two screw flights arranged offset from one another in a circumferential direction in regular intervals defined by 360° divided by the number of screw flights, and are of uniform design; and wherein each of the screw flights has a plurality of recesses in the circumferential direction and the recesses of one screw flight are offset in the axial direction from the recesses of another screw flight.

31. The screw conveyor according to claim 30, wherein in the screw flight in the circumferential direction within an angular range of 360° at least one recess is arranged; or each screw flight has several spaced recesses and the recesses each have a longitudinal extension along a recess longitudinal axis, wherein the recess longitudinal axis is oriented obliquely, at an angle of at least 2.5°, relative to a thread running direction of the screw flight, so that compared to the thread running direction of the screw flight the recess longitudinal axis is oriented further in the direction of the axial direction.

32. The screw conveyor according to claim 30, wherein each screw flight has several spaced recesses; the recesses each have a length in a thread running direction of the screw flight and a width in a width direction of the screw flight, and the length is at least twice as great as the width, wherein the length of the recesses is at least half as long as the distance between the recesses; or the length of the recesses and the distance between the recesses are selected such that, during one full rotation of the screw conveyor about the axis of rotation, each point of a surface of rotation spanned by the outer circumference of the screw flight is swept by at least one of the recesses; or the recesses are arranged at a uniform distance from each other in the circumferential direction on the screw flight; or the recesses each have an opening in the outer edge of the screw flight, wherein the opening has a contour with at least two, acute angles, with an angle less than 90°.

33. The screw conveyor according to claim 24, wherein a cross-sectional profile of the screw flight has a negative flank angle on at least one side in at least one section, in the form of a linear course of the cross-sectional profile side or in the form of a course of a continuous function such as a parabola; and the screw flight has an inner diameter and an outer diameter and the screw flight is formed wider in the region of the outer diameter than in the region of the inner diameter, wherein the screw flight is formed at least twice as wide in the region of the outer diameter as in the region of the inner diameter.

34. The screw conveyor according to claim 24, wherein the screw conveyor has an envelope which tapers from a first end of the screw conveyor to a second end of the screw conveyor.

35. A separator device for dewatering moist masses, including liquid manure and/or digestates, comprising: a drive shaft rotatably mounted about a drive axis of rotation; a screw conveyor according to claim 24, wherein the screw conveyor is connected to the drive shaft for torque transmission from the drive shaft to the screw conveyor; and a screening device enclosing at least part of the screw conveyor, wherein the screening device has a liquid-permeable screen wall for dewatering the moist mass.

36. The separator apparatus according to claim 35, wherein a cross-sectional profile of the screw flight has a negative flank angle on at least one side in at least one section, in the form of a linear course of the cross-sectional profile side or in the form of a course of a continuous function such as a parabola; and the screw flight has an inner diameter and an outer diameter and the screw flight is formed wider in the region of the outer diameter than in the region of the inner diameter, wherein the screw flight is formed at least twice as wide in the region of the outer diameter as in the region of the inner diameter; and wherein the screening device extends from a first end to a second end and has an inner wall which is rotationally symmetrical about the drive axis of rotation, whose inner diameter tapers from the first end to the second end, wherein the screw conveyor is axially adjustable relative to the screening device by means of an axial adjustment device.

37. A method for manufacturing a screw conveyor according to claim 24, the method comprising the steps of: providing a shaft which extends in an axial direction along an axis of rotation as a machined or preformed shaft; performing additive manufacturing of a screw flight on the shaft by layer-by-layer material deposition, comprising: applying a metallic path by means of melting a metal material, wherein the path extends along a thread running direction of the screw flight; and applying further paths, which are arranged parallel to the applied path.

38. The method according to claim 37, wherein the screw flight is built up in layers such that the screw flight has a cross-sectional profile with a width in the region of the outer circumference of the screw flight and a width in the region of the inner circumference of the screw flight and the width in the region of the outer circumference of the screw flight is greater than the width in the region of the inner circumference of the screw flight; and the screw flight is built up in layers in such a way that the screw flight has, on the outer circumference of the screw flight, several recesses spaced apart from one another for receiving fiber-containing solids.

39. The method according to claim 37, further comprising the steps of: determining the height of an already applied path in a radial direction; applying a metallic path by means of melting a metal material in a layer lying radially above the already applied path, wherein the positions at which the metal material is melted off for application of this path is set in dependence of the previously determined height of the already applied path; and applying several layers arranged one above the other in the radial direction, each having at least one path, to form a layer stack until the layer stack reaches and/or exceeds a nominal height, wherein before the application of each new layer the height of at least one path of the previously applied layer in radial direction is determined.

40. The method according to claim 39, wherein the determination of the height of the applied path in the radial direction is performed by means of the following steps: placing a surface of a welding head or a metal wire protruding from a welding head and, which has a known length, on the surface of the applied path, by detecting a contact force or detecting an electrical connection between the welding head or the metal wire and the applied path; and determining the position of the surface of the deposited path in dependence of the position of the welding head when placing the metal wire on the applied path or a length of the metal wire.

41. The method according to claim 39, wherein the determination of the height of the applied path in radial direction is performed by means of the following steps: placing a surface of a welding head or a metal wire protruding from a welding head, which has a known length, on a reference plane; applying a metallic path by means of melting off the metal wire; if necessary, again placing the metal wire protruding from the welding head on the reference plane for determination of the length of the metal wire; placing the surface of the welding head or the metal wire on the surface of the applied path and detection of the placement of the surface of the welding head or the metal wire on the surface, by detecting a contact force or detecting an electrical connection between the surface of the welding head or the metal wire and the applied path; and determining the position of the surface of the applied path in dependence of the position of the welding head during placing of the surface of the welding head or the metal wire on the applied path or a length of the metal wire.

42. The method according to claim 37, wherein the manufacture of the screw conveyor takes place by wire-based additive manufacturing by means of arc welding, including gas metal arc welding (GMAW), metal inert gas welding (MIG), and/or metal active gas welding (MAG), by means of at least one welding robot.

43. The method according to claim 42, further comprising the steps of: chip removal of additively applied material at the outer circumference of the screw flight for reduction of the roughness of the screw flight at the outer circumference of the screw flight and/or for production of a straight outer edge at the outer circumference of the screw flight; and chip removal of additively applied material on the flanks of the screw flight for reduction of the roughness of the screw flight on the flanks of the screw flight.

44. The method according to claim 42, wherein the shaft is clamped in a holder and is rotatable about the axis of rotation by means of movement of the holder; and the at least one welding robot has at least two electromechanically driven axes.

45. The method according to claim 42, wherein the layered buildup of the screw flight is carried out by application of paths arranged in parallel, wherein the paths run along a thread running direction of the screw flight, wherein a part of the paths is formed continuously along the entire screw flight in each case, a part of the paths has interruptions in each case in the region of the recesses and is not formed continuously along the entire screw flight, or a recess is formed by the course of the paths.

46. The method according to claim 37, wherein the number of parallel paths in the inner diameter of the screw flight is less than the number of parallel paths in the area of the outer diameter of the screw flight.

47. The method according to claim 37, further comprising the step of: creating production data for the positioning of the melting off of the metal wire when applying the path, comprising the steps: creating a digital basic structure mapping cross-sectional information comprising a nominal height and a width dependent on the height of a screw flight; and replicating the digital basic structure in a predetermined threading motion that corresponds to the thread shape of the screw flight.

48. A use of a screw conveyor according to claim 24, in a separator device, for dewatering moist masses, including digestates and/or liquid manure, wherein a cross-sectional profile of the screw flight has a negative flank angle on at least one side in at least one section, in the form of a linear course of the cross-sectional profile side or in the form of a course of a continuous function such as a parabola; and the screw flight has an inner diameter and an outer diameter and the screw flight is formed wider in the region of the outer diameter than in the region of the inner diameter, wherein the screw flight is formed at least twice as wide in the region of the outer diameter as in the region of the inner diameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Preferred embodiments are explained by way of example with reference to the accompanying figures. It shows:

[0104] FIG. 1 is a schematic perspective representation of a section of a screw conveyor with two screw flights arranged 180° offset from each other, wherein only a section of half a rotation of the two screw flights is shown;

[0105] FIG. 2 is a schematic side view of the section shown in FIG. 1 of a screw conveyor with two screw flights arranged 180° offset from each other;

[0106] FIG. 3 is a schematic side view of the section shown in FIG. 1 of a screw conveyor with two screw flights arranged 180° offset from each other;

[0107] FIG. 4 is a schematic view in direction of the axis of rotation of the section shown in FIG. 1 of a screw conveyor with two screw flights arranged 180° offset from each other;

[0108] FIG. 5a is a schematic view of a first intermediate state of a screw conveyor during the manufacturing of the screw conveyor;

[0109] FIG. 5b is a schematic view of a second intermediate state of a screw conveyor during the manufacturing of the screw conveyor;

[0110] FIG. 5c is a schematic view of a third intermediate state of a screw conveyor during the manufacturing of the screw conveyor;

[0111] FIG. 6 is a schematic representation of a separator device with a screw conveyor; and

[0112] FIG. 7 is an exemplary schematic sequence of a method for additive manufacturing of a screw conveyor.

[0113] In the figures, identical or essentially functionally identical or similar elements are designated with the same reference signs. Dashed lines shown in gray in the figures indicate in particular contours that are covered by a component.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0114] FIG. 1 shows a schematic perspective representation of a section of a screw conveyor 10 with two screw flights 20, 30 arranged 180° offset from each other, wherein only a section of half a rotation of the two screw flights 20, 30 is shown. A screw conveyor 10 described herein can in particular be formed to be considerably longer than in the figures shown herein (in which it is shown only in section), in which case each screw flight 20, 30 has several rotations about the shaft 11. The screw flights 20, 30 are arranged in a thread-like manner on the shaft 11 and were applied to the shaft 11 in layers by means of additive manufacturing. The width of screw flights 20, 30 in the region of the inner circumference of the screw flights 20, 30 is smaller than the width of the screw flights 20, 30 in the region of the outer circumference of the screw flights 20, 30, respectively. In the region of the outer circumference, the screw flight 20 has a plurality of recesses 21 spaced apart from each other. The screw flight 30 also has a plurality of recesses spaced apart from each other. The screw flights have a cross-sectional profile with a width in the region of the outer circumference 20c of the screw flight 20 and a width in the region of the inner circumference 20a of the screw flight 20. The width 20c in the region of the outer circumference of the screw flight is thereby larger than the width 20a in the region of the inner circumference of the screw flight. Between the inner and outer regions, a central region 20b is arranged in which the cross section is formed to become wider towards radially outwards.

[0115] FIG. 2 shows a schematic side view of the section shown in FIG. 1 of a screw conveyor with two screw flights 20, 30 arranged 180° offset from each other that are mounted on a shaft 11. The shaft 11 can be rotatably mounted about an axially extending axis of rotation 300. The shaft 11 is cylindrical formed as a hollow shaft. The shaft 11 has an outer circumference 11a and an inner circumference 11b (shown by a gray dashed line).

[0116] FIG. 3 shows a schematic side view of the section shown in FIGS. 1-2 of a screw conveyor with two screw flights 20, 30 arranged 180° offset from each other. The section shown is the section shown in FIG. 2, but wherein the screw conveyor is rotated 90° about the axis of rotation 300 compared to the representation in FIG. 2.

[0117] FIG. 4 shows a schematic view in direction of the axis of rotation of the section of a screw conveyor shown in FIGS. 1-3 with two screw flights arranged 180° offset from each other. Thereby, the cross section which widens radially outward or the cross-sectional profile which widens radially outward of the screw flights 20, 30 can be seen.

[0118] At the screw flight 20, the negative flank angle a is drawn in a region. The region in which the flank angle a is negative is arranged between a radially inner and a radially outer region, wherein in the radially inner and the radially outer region the flank angle is not negative but is 0°.

[0119] FIG. 5a shows a schematic view of a first intermediate state of a screw conveyor during the manufacturing of the screw conveyor. First layers 20a, 30a, each consisting of a plurality of metallic paths arranged in parallel, have been applied to the shaft. The layers have thereby been applied on top of each other radially outwards.

[0120] FIG. 5b shows a schematic view of a second intermediate state of a screw conveyor during the manufacturing of the screw conveyor. After the state shown in FIG. 5a, further layers 20b, 30b, which become wider radially outward, were applied in layers.

[0121] FIG. 5c shows a schematic view of a third intermediate state of a screw conveyor during the manufacturing of the screw conveyor. After the state shown in FIG. 5b, further layers 20c, 30c positioned in the area of the outer circumference of the screw flights 20, 30 were applied in layers. Thereby, the metallic paths were interrupted in the area of the recesses 21 when the metallic tracks were applied, so that the recesses were created during the additive manufacturing of the screw flights without the need to subsequently introduce the recesses by milling or other mechanical processing.

[0122] FIG. 6 shows a schematic sectional view of a preferred embodiment of a separator device 200. The separator device 200 is configured to dewater a moist mass M in order to provide a dewatered mass S with a desired dry mass content. For this purpose, the separator device 200 has a drive shaft 50 which is rotatably mounted about an axis of rotation and extends in an axial direction. The drive shaft 50 is driven by a motor shaft of a drive unit 40.

[0123] For conveying the moist mass M to be dewatered in a conveying direction F and for separating the liquid L from the mass M to be dewatered to provide a dewatered mass S having a desired dry mass content, a screw conveyor 10 is rotatably arranged within a screening device 70 so that the screening device 70 surrounds the screw conveyor 10.

[0124] The screw conveyor 10 and the screening device 70 are designed in such a way that the screw conveyor 10 lies tightly against the screening device 70, in particular, against an inner screen surface of a fluid-permeable screen wall of the screening device 70. Due to this arrangement, the moist mass M to be dewatered is compressed via an inlet chamber 51 in the conveying direction F between the screw conveyor 10 and the screening device 70 in dependence of an existing conveying pressure. This causes the liquid L from the moist mass M to be pressed through the fluid-permeable screen wall of the screening device. The fluid-permeable screen wall has outlet openings, which extend between the inner screen surface of the screen wall, which faces the screw conveyor 10, and an outer screen surface of the screen wall, which is radially outer with respect to the inner screen surface and faces away from the screw conveyor 10. Through the outlet openings, the liquid L separated from the moist mass M can emerge from the screening device 70 and be collected in a container 61. The dewatered mass S exits the separator device and can for example be collected in a container 62.

[0125] The size of the outlet openings is designed in such a way that the liquid L, but not the solids of the moist mass M, can exit the screening device 70 through the screen wall, so that the solids of the moist mass M are guided through the screening device 70 to an outlet.

[0126] FIG. 7 an exemplary schematic sequence of a method 100 for additive manufacturing of a screw conveyor, wherein the manufacturing of the screw conveyor takes place by wire-based additive manufacturing using gas metal arc welding (GMAW) using a welding robot, comprising the steps:

[0127] In step 101, providing a shaft extending in axial direction along an axis of rotation. In step 102, additive manufacturing of a screw flight on the shaft by layer-by-layer material deposition, comprising the steps 102a, applying a metallic path by means of melting off a metal wire, wherein the path preferably extends along the thread running direction of the screw flight, and 102b, applying further paths that are arranged parallel to the applied paths. Thereby, the screw flight is built up in layers in such a way that the screw flight has a cross-sectional profile having a width in the region of the outer circumference of the screw flight and a width in the region of the inner circumference of the screw flight, and the width in the region of the outer circumference of the screw flight is larger than the width in the region of the inner circumference of the screw flight. In addition, the screw flight is built up in layers in such a way that the screw flight has a plurality of recesses spaced apart from each other at the outer circumference of the screw flight for receiving, in particular fiber-containing, solids.

[0128] In step 103, determining the height of an already applied path in radial direction, wherein determining the height of the applied path in radial direction is performed by means of the following steps: placing the metal wire, which has a known length, on a reference plane, applying a metallic path by means of melting off the metal wire, placing the metal wire again on the reference plane for determination of the length of the metal wire, placing the metal wire on the applied path, determining the height of the applied path in dependence of the position of the metal wire when placing the metal wire on the applied path and of the length of the metal wire. Based on the determination of the actual height of an applied layer that is possible in this way, it is also possible to specify a nominal application height and to calculate the number of layers required to achieve this nominal application height.

[0129] In step 104, application of a metallic path by means of melting off a metal wire in a layer lying radially above the already applied path, wherein the positions at which the metal wire is melted off for application of this path is set in dependence of the previously determined height of the already applied path. In step 105, applying several layers arranged one above the other in radial direction, each with at least one path, until a nominal height is reached and/or exceeded, wherein preferably the height of at least one path of the previously applied layer in the radial direction is determined before applying each new layer.

[0130] In step 106, chip removal of additively applied material on the outer circumference of the screw flight for reduction of the roughness of the screw flight on the outer circumference of the screw flight and/or for production of a straight outer edge on the outer circumference of the screw flight. In step 107, chip removal of additively applied material on the flanks of the screw flight for reduction of the roughness of the screw flight on the flanks of the screw flight.